compositor: Drop unneeded create_output callback
compositor: Drop unneeded create_output callback

Signed-off-by: Bryce Harrington <bdb14cfc1ab8d24e13de84adc40b41ae60c13bd1@osg.samsung.com>
Reviewed-by: Giulio Camuffo <65adf162ac3b23aefeb12d72b964c762bc76d738@gmail.com>
Reviewed-by: Pekka Paalanen <0f6ae7001e34c37b02fb2c1c2573ddf8f442136a@collabora.co.uk>

giucam/weston,krezovic/weston,sir-murray/weston,Gnurou/weston,giucam/weston,Gnurou/weston,krezovic/weston,sir-murray/weston